PREFACE TO SECOND EDITION. Some readers might prefer that less space should be devoted to theoretical matter and more to descriptions of apparatus, but in my opinion the place for such information is in the trade periodicals. It takes so long to print a book that drawings are antiquated when the issue appears, but the fundamental principles of metallurgy remain the same. A book issued in England refers courteously to the former edition of this work, but states that little information is given concerning the practical details of operation. That same book sets forth that an open-hearth furnace ;s charged by putting the pig-iron in first; that in a twenty-five-ton furnace not over nine men can be employed, even when there are doors on both sides, and that with rapid work it takes two hours to charge a heat. Now those figures are true for the district with which that writer was familiar, but in America the pig-iron is put in last, while at Steel-ton on a furnace of the size mentioned we use twice the number of men and with good scrap finish the work by charging, by hand labor only, in a period ranging from thirty minutes down to eleven minutes. Of equal value is much of the so-called practical information given in metallurgical treatises. It only remains to thank many friends, both at home and abroad, for aiding in this work which has been accomplished in the intervals of what I trust is n.ot otherwise an entirely idle life. H. H. CAMPBELL. Steelton, Pa.} December, 1908.